A new bout of violence in the Central African Republic, where two Moroccan peacekeepers were killed Tuesday, risks derailing years of efforts to restore a fragile stability, the United Nations warned Wednesday.

U.N. Secretary-General Antonio Guterres condemned the killing of the peacekeepers, who were ambushed in the southeast town of Bangassou on Tuesday.

The U.N. chief called on all parties to stop the violence and "take action to avoid a further deterioration of the fragile security situation in the country.''

The country is struggling to emerge from a civil war that erupted in 2013 following the overthrow of former President Francois Bozize, a Christian, by Muslim rebels from the Seleka coalition.

The coup led to the formation of "anti-balaka" (anti-machete) vigilante units of Christians who began to target Muslims. Both sides committed widespread atrocities.

Tuesday's raid, which injured a third soldier, followed similar attacks by suspected anti-balaka fighters in the diamond-mining town in recent days, including one on Sunday that killed a Moroccan peacekeeper and left three others wounded.

The latest incidents prompted 14 humanitarian workers from six organizations to suspend activities in the town, east of Bangui on the Congolese border.

Violence has escalated since former colonial power France ended its peacekeeping mission in the country last year. It continues despite a peace deal signed in Rome last month between the government and rival factions.